Rotatable cartridge for processing and analyzing a biological sample and dispensing method therewith

ABSTRACT

An automatic analyzer cartridge, spinnable about a rotational axis, has fluid and aliquoting chambers, a metering chamber connected to a vent that is nearer to the rotational axis than the metering chamber, first and second ducts connecting the fluid and aliquoting chambers, and the metering and aliquoting chambers, respectively. Metering chamber side walls taper away from a central region, wherein capillary action next to the walls is greater than in the central region. Fluid flows to the metering chamber using capillary action via the second duct that has an entrance and exit in the aliquoting and metering chambers, respectively; the exit being closer to the rotational axis than the entrance. A downstream fluidic element connects to the metering chamber via a valve. A fluidic structure receives and processes a biological sample into the processed biological sample and has a measurement structure that enables measurement of the processed biological sample.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No. 15/943,093 filed Apr. 2, 2018, which is a continuation of U.S. application Ser. No. 15/352,672, filed Nov. 16, 2016, now U.S. Pat. No. 9,962,699, which is a continuation of International Application No. PCT/EP2015/062337, filed Jun. 3, 2015, which claims priority to European patent application No. EP14171424.6, filed Jun. 6, 2014.

TECHNICAL FIELD

The inventive embodiments disclosed herein relate to analytical test devices for biological samples, in particular to the design and use of rotatable cartridges for performing a measurement of a biological sample.

BACKGROUND AND RELATED ART

Two classes of analysis systems are known in the field of medical analysis: wet analysis systems, and dry-chemical analysis systems. Wet analysis systems, which essentially operate using “wet reagents” (liquid reagents), perform an analysis via a number of required step such as, for example, providing a sample and a reagent into a reagent vessel, mixing the sample and reagent together in the reagent vessel, and measuring and analyzing the mixture for a measurement variable characteristic to provide a desired analytical result (analysis result). Such steps are often performed using technically complex, large, line-operated analysis instruments, which allow manifold movements of participating elements. This class of analysis system is typically used in large medical-analytic laboratories.

On the other hand, dry-chemical analysis systems operate using “dry reagents” which are typically integrated in a test element and implemented as a “test strip”, for example. When these dry-chemical analysis systems are used, the liquid sample dissolves the reagents in the test element, and the reaction of sample and dissolved reagent results in a change of a measurement variable, which can be measured on the test element itself. Above all, optically analyzable (in particular colorimetric) analysis systems are typical in this class, in which the measurement variable is a color change or other optically measurable variable. Electrochemical systems are also typical in this class, in which an electrical measurement variable characteristic for the analysis, in particular an electrical current upon application of a defined voltage, can be measured in a measuring zone of the test element using electrodes provided in the measuring zone.

The analysis instruments of the dry-chemical analysis systems are usually compact, and some of them are portable and battery-operated. The systems are used for decentralized analysis, for example, at resident physicians, on the wards of the hospitals, and in so-called “home monitoring” during the monitoring of medical-analytic parameters by the patient himself (in particular blood glucose analysis by diabetics or coagulation status by warfarin patients).

In wet analysis systems, the high-performance analysis instruments allow the performance of more complex multistep reaction sequences (“test protocols”). For example, immunochemical analyses often require a multistep reaction sequence, in which a “bound/free separation” (hereafter “b/f separation”), i.e., a separation of a bound phase and a free phase, is necessary. According to one test protocol, for example, the probe can first be transported through a porous solid matrix, which contains a specific binding reagent for the analyte. A marking reagent can subsequently be caused to flow through the porous matrix, to mark the bound analyte and allow its detection. To achieve precise analysis, a washing step must be performed, in which unbound marking reagent is completely removed. Numerous test protocols are known for determining manifold analytes, which differ in manifold ways, but which share the feature that they require complex handling having multiple reaction steps, in particular also a b/f separation possibly being necessary.

Test strips and similar analysis elements normally do not allow controlled multistep reaction sequences. Test elements similar to test strips are known, which allow further functions, such as the separation of red blood cells from whole blood, in addition to supplying reagents in dried form. However, they normally do not allow precise control of the time sequence of individual reaction steps. Wet-chemical laboratory systems offer these capabilities, but are too large, too costly, and too complex to handle for many applications.

To close these gaps, analysis systems have been suggested which operate using test elements which are implemented in such a manner that at least one externally controlled (i.e., using an element outside the test element itself) liquid transport step occurs therein (“controllable test elements”). The external control can be based on the application of pressure differences (overpressure or low-pressure) or on the change of force actions (e.g., change of the action direction of gravity by attitude change of the test element or by acceleration forces). The external control is especially frequently performed by centrifugal forces, which act on a rotating test element as a function of the velocity of the rotation.

Analysis systems having controllable test elements are known and typically have a housing, which comprises a dimensionally-stable plastic material, and a sample analysis channel enclosed by the housing, which often comprises a sequence of multiple channel sections and chambers expanded in comparison to the channel sections lying between them. The structure of the sample analysis channel having its channel sections and chambers is defined by profiling of the plastic parts. This profiling is able to be generated by injection molding techniques or hot stamping. Microstructures, which are generated by lithography methods, are increasingly being used more recently, however.

Analysis systems having controllable test elements allow the miniaturization of tests which have only been able to be performed using large laboratory systems. In addition, they allow the parallelization of procedures by repeated application of identical structures for the parallel processing of similar analyses from one sample and/or identical analyses from different samples. It is a further advantage that the test elements can typically be produced using established production methods and that they can also be measured and analyzed using known analysis methods. Known methods and products can also be employed in the chemical and biochemical components of such test elements.

In spite of these advantages, there is a further need for improvement. In particular, analysis systems which operate using controllable test elements are still too large. The most compact dimensions possible are of great practical significance for many intended applications.

U.S. Pat. No. 8,114,351 B2 discloses an analysis system for the analysis of a body fluid sample for an analyte. The analysis system provides a test element and an analysis instrument having a dosing station and a measurement station. The test element has a housing an (at least) one sample analysis channel enclosed by the housing. The test element is rotatable around an axis of rotation which extends through the test element.

U.S. Pat. No. 8,470,588 B2 discloses a test element and a method for detecting an analyte. The test element is essentially disk shaped and flat, and can be rotated about a preferably central axis which is perpendicular to the plane of the disk shaped test element.

Kim, Tae-Hyeong, et al. “Flow-enhanced electrochemical immunosensors on centrifugal microfluidic platforms.” Lab on a Chip 13.18 (2013): 3747-3754, doi:10.1039/c3lc50374g, (hereafter “Kim et. al.”) discloses a fully integrated centrifugal microfluidic device with features for target antigen capture from biological samples, via a bead-based enzyme-linked immune-sorbent assay, and flow-enhanced electrochemical detection. This is integrated into a Centrifugal microfluidic discs, also known as “lab-on-a-disc” or microfluidic CDs.

Martinez-Duarte, Rodrigo, et al. “The integration of 3D carbon-electrode dielectrophoresis on a CD-like centrifugal microfluidic platform.” Lab on a Chip 10.8 (2010): 1030-1043, doi:10.1039/B925456K, (hereafter “Martinez-Duarte et. al.”) discloses a dielectrophoresis (DEP)-assisted filter with a compact disk (CD)-based centrifugal platform. 3D carbon electrodes are fabricated using the C-MEMS technique and are used to implement a DEP-enabled active filter to trap particles of interest.

European patent application publication EP 2 302 396 A1 discloses an analyzing device includes: an operation cavity that is adjacent to a first reserving cavity retaining a sample liquid, in a circumferential direction of rotational driving; a connecting section provided on a side wall of the first reserving cavity to suck the sample liquid by a capillary force and transfer the sample liquid to the operation cavity; and second reserving cavities that are disposed outside the operation cavity in the circumferential direction of the rotational driving and communicate with the outermost position of the operation cavity through a connecting passage. The connecting section is circumferentially extended farther than the liquid level of the sample liquid retained in the first reserving cavity.

United States patent application publication US 2009/0246082 discloses an analysis device comprising a separation chamber for separating a sample solution into a solution component and a solid component, a holding channel for holding a predetermined amount of the separated solid component, a mixing chamber connected to the holding channel, an overflow channel connected between the holding channel and the separation chamber, a sample overflow chamber into which the sample solution remaining in the separation chamber is discharged, and a joint channel connecting the separation chamber and the sample overflow chamber. After the separated solution component fills the overflow channel with priority by a capillary force, the separated solid component is transferred to the holding channel via the overflow channel, and a predetermined amount of the solid component is measured. The solid component in the holding channel is transferred to the mixing chamber by a centrifugal force, and simultaneously, the sample solution remaining in the separation chamber is discharged to the sample overflow chamber by the siphon effect of the joint channel.

SUMMARY

A method of performing a measurement of a processed biological sample, a cartridge and an automatic analyzer are disclosed in the independent claims. Additional embodiments are given in the dependent claims.

In one aspect the invention, an embodiment provides for a method of performing a measurement of a processed biological sample using a cartridge.

A cartridge as used here encompasses a test element for processing the biological sample into a processed biological sample. The cartridge may include structures or components which enable a measurement to be performed on the biological sample. A cartridge is a test element as is defined and explained in U.S. Pat. Nos. 8,114,351 B2 and 8,470,588 B2. A cartridge as used herein may also be referred to as a Centrifugal microfluidic disc, also known as “lab-on-a-disc” or a microfluidic CD.

A biological sample as used herein encompasses also any chemical product derived, copied, replicated, or reproduced from a sample taken from an organism.

The cartridge is operable for being spun around a rotational axis. The cartridge comprises a fluid chamber for receiving a fluid. In various contexts receiving the fluid may have different meaning. In one interpretation receiving the fluid may for example be receiving a fluid via a pipette or other dispenser. In other situations the receiving of the fluid may be from opening a reservoir within the cartridge. The cartridge further comprises an aliquoting chamber. The cartridge further comprises a first duct connecting the fluid chamber and the aliquoting chamber. The cartridge further comprises a metering chamber. The metering chamber is operable for causing fluid to fill the metering chamber using capillary action.

Capillary action as used herein may also refer to capillarity, capillary motion, or wicking, or capillary force. Capillary action is the ability of a liquid to flow in narrow spaces without the assistance of external forces like gravity or centrifugal forces.

Capillary action is caused by intermolecular forces between the liquid and adjacent solid surfaces. Adhesive forces between the liquid and the adjacent solid surfaces can be used to counteract gravity or other external forces. In some cases the capillary action can be increased by decreasing the distance between adjacent solid surfaces.

The cartridge further comprises a second duct connecting the metering chamber with the aliquoting chamber. The second duct comprises a duct entrance in the aliquoting chamber. The second duct further comprises a duct exit in the metering chamber. The duct exit is closer to the rotational axis than the duct entrance. The second duct is operable for causing fluid flow to flow into the metering chamber using capillary action. The cartridge further comprises a downstream fluidic element. The downstream fluidic element is connected to the metering chamber via a valve. The downstream fluidic element is downstream in the sense that fluid flows from the metering chamber to the downstream fluidic element.

The cartridge further comprises a fluidic structure for processing a biological sample into the processed biological sample. The fluidic structure comprises the downstream fluidic element. The fluidic structure comprises the downstream fluidic element. The downstream fluidic element is fluidically connected to the fluidic structure. The downstream fluidic element may be considered to be a component or a part of the fluidic structure. The fluidic structure comprises a measurement structure for enabling measurement of the processed biological sample. The fluidic structure is configured for receiving the biological sample. For instance the cartridge may have an entrance receptacle adapted for receiving the biological sample.

The method comprises the step of placing the biological sample into the fluidic structure. The method further comprises the step of controlling the rotational rate of the cartridge to process the biological sample into the processed biological sample using the fluidic structure. By controlling the rotational rate and the duration at different rotational rates the disc or cartridge can be used to process the biological sample into the processed biological sample. The method further comprises the step of filling the fluid chamber with the fluid. In different embodiments this may be achieved in different ways, for example a reservoir within the cartridge may be opened or an external source may be used to dispense fluid into the fluid chamber. The method further comprises the step of controlling the rotational rate of the cartridge to transport the fluid from the fluid chamber to the aliquoting chamber via the first duct. In different embodiments this may be achieved in different ways, for instance in some examples the fluid chamber could be closer to the axis of rotation than the aliquoting chamber. In this case, by increasing the rotational rate the fluid may be forced through the first duct using a centrifugal force. In other examples the first duct may for instance be a siphon. The siphon for example may cause fluid to flow automatically by using capillary action and centrifugal forces. In this case reducing the rotational rate of the cartridge may cause fluid to fill the siphon and an increase of the rotational rate may cause the fluid to flow from the fluid chamber to the aliquoting chamber.

The method further comprises decreasing the rotational rate of the cartridge to permit the fluid in the reservoir to flow into the second duct and to fill the metering chamber a first time. Capillary forces cause the fluid to flow from the aliquoting chamber to the second duct and then to the metering chamber. The spinning of the cartridge with the centrifugal force may be used to counteract this capillary force. When the rotational rate of the cartridge is slowed down this then allows the capillary action to draw the fluid into the metering chamber. Also the act of decreasing the rotational rate of the cartridge may cause forces on the fluid which cause the fluid to be forced into the metering chamber. The method further comprises the step of increasing the rotational rate of the cartridge to transfer a first part of the fluid from the metering chamber through the valve and to transfer a first remaining part back to the aliquoting chamber.

The method further comprises the step of decreasing the rotational rate of the cartridge to permit the fluid in the reservoir to flow into the second duct and to fill the metering chamber a second time. The method further comprises the step of increasing the rotational rate of the cartridge to transfer a second part of the fluid from the metering chamber through the valve and to transfer a second remaining part back into the aliquoting chamber. Although this is described in reproducing the aliquoting of the fluid two times, the aliquotation of the fluid may be repeated over and over again as long as there is enough fluid within the aliquoting chamber to effectively fill the metering chamber. The method further comprises the step of performing the measurement using the measurement structure and using a measurement system.

This method may have the advantage that the fluid can be transferred from the aliquoting chamber multiple times to the downstream fluidic element. In some examples the measurement is an optical measurement. The measurement may include, but is not limited to: a photometric transmission measurement, a measurement of the scattering of light, a chemiluminescence, a fluorescence, and electrochemiluminescense (ECL) measurement.

This method may be beneficial because it may provide a means of performing multiple aliquotations of the fluid into the downstream fluidic element.

In another embodiment, the metering chamber has side walls and a central region. The side walls taper away from the central region. Capillary action next to the side walls of the metering chamber is greater than in the central region of the metering chamber.

In another embodiment the cartridge further comprises a vent which is connected to the metering chamber. The vent is nearer to the rotational axis than the metering chamber. The vent for example may be connected such that gas is able to enter or exit the metering chamber. This may enable fluid to enter or exit the metering chamber.

In another embodiment, the cartridge further comprises an expansion chamber with a vent. The expansion chamber is connected to the metering chamber. The capillary action in the metering chamber is greater than capillary action in the expansion chamber. The expansion chamber is nearer to the rotational axis than the metering chamber.

In another embodiment the interface between the metering chamber and the expansion chamber is formed as a capillary valve or a capillary stop valve. In this embodiment the cross section of the metering chamber increases step like towards the larger cross section of the expansion chamber. Thereby the fluid will not flow from the metering chamber into the expansion chamber if no additional forces are applied.

This embodiment may have the advantage that the metering chamber fills first at the side walls surrounding the central region and thereafter at the central region. This fills the metering chamber in a predictable and controllable way that reduces the chances that bubbles will form or adhere.

The formation of bubbles prevent most microfluidic structures from being used more than once for dispensing a metered amount of fluid. For example, the patent application US 2009/0246082 A1 teaches the use of air holes which are positioned in various locations in an overflow chamber or channel. See for example FIGS. 3, 4, and 5 of US 2009/0246082 A1. The chamber of 13 of FIG. 5(a) is essentially a siphon. The positioning of an air hole at the bend of a siphons as is depicted in FIG. 5(a) however does not enable the repeatable aliquoting of fluid in the way that having a metering camber with side walls and a central region as described above. This potential advantage is described in greater detail below.

Similarly an aliquoting structure described in EP 2302396 A1 enables parallel splitting of fluid in several aliquots, but also uses a venting structure that only lets air in at the position nearest to the rotational axis. For example see FIG. 55 of EP 2302396 A1 and the accompanying text. The structure shown in the picture features a long capillary channel that has to be filled by fluid. The channel features several vents and connections to downstream chambers.

In FIG. 42 of EP 2302396 A1 a siphon 215b connects a chamber 210b with another chamber 209c. Placing a vent at the point of siphon 215b closest to the rotational axis 107 would not enable the reliable aliquotation of the same amount of fluid every time due to the risk of bubble formation. The structures shown in EP 2302396 has the following drawbacks: The refilling of such a structure for a second aliquoting step is highly unreliable. For a second aliquoting step the capillary has to be filled again. As the walls of the capillary are still wet the filling process differs from the initial filling process of the first aliquoting step. The fluid moves significantly faster along the channel walls than along the channels center. Due to the small channel diameter fluid progressing on one channel wall often gets in contact with fluid the other channel wall. This causes the formation of an air bubble that clogs the channel. This effect is significantly increased if fluids with low surface tension (e.g. washing buffers) are aliquoted. The probability of air bubble formation rises with the length of the capillary to be filled.

Experiments conducted show that long capillaries cannot be reliably used in repetitive aliquoting steps. A structure with a single long capillary and a vent near the bend was constructed. During the tests air bubbles clogged the vent consistently when a second aliquotation of the liquid is attempted.

The present embodiment may have a further advantage by that enables serial and accurate aliquoting steps. A “closed” capillary with four walls can be completely avoided in this structure. In some examples, the fluid may pass the second duct and reach the metering chamber due to the inertia of the fluid by stopping the rotation of the disk with a negative acceleration. In some examples, the second duct does not act as capillary. In some embodiments, the fluid may pass the second duct and reach the metering chamber due both capillary forces and forces caused by inertia. In the metering chamber the side walls may function as guidance structures at the outer walls guide the fluid due to a higher capillary action than the central region. After the side walls have filled, the central part of the metering chamber may also fill by capillary forces. The guidance structure features a “open” capillary structure comprising three walls preventing air bubble formation or adhesion. The edge of the metering chamber closest to the rotational axis borders an expansion chamber. In some examples the central part of the metering chamber borders the expansion chamber over its whole width. This may avoid or reduce the risk of air bubble formation in the metering chamber which may enable the precise metering and reliable refilling of the metering chamber for multiple subsequent aliquotations using the same microfluidic structure.

In addition to the potential advantages describe above, the fluidic structure in US 2009/0246082 has the additional disadvantage when compared to the present embodiment. The overflow chamber 15 (see FIG. 5(c) of US 2009/0246082) serves to maintain and hold surplus fluid which is in contrast to the present embodiment. Surplus fluid will become trapped in the overflow chamber 15. In the present embodiment, the fluid in the aliquoting chamber may be able to be transferred to the metering chamber.

In some embodiments the first part of the fluid has the same volume as the second part of the fluid. In some embodiments the first remaining part has the same volume as the second remaining part.

The first and second remaining parts are the part of the fluid which is in the metering chamber but is transferred back into the aliquoting chamber when the rotational rate of the cartridge is increased.

In some embodiments the rotation of the cartridge is such that the direction of rotation passes through the aliquoting chamber first and then the metering chamber. When this is done this way, when the cartridge is decelerated the inertia of the fluid naturally forces it into the second duct and assists the filling of the metering chamber.

In another embodiment during performing the method the cartridge is oriented in a horizontal direction. Alternatively, the axis of rotation may be described as being vertical.

In another embodiment the valve is a capillary valve or a capillary stop valve.

A capillary valve or capillary stop value as used herein is a valve or structure which uses the capillary force of a fluid to prevent fluid from flowing through the capillary stop valve. For example a tube with a sufficiently small diameter will draw fluid into it and the capillary force will prevent the fluid from flowing out of the tube. For the case of this tube the entrance and exit of the tube function as capillary stop valves. In some examples the siphon exit itself may have dimensions small enough (compared to the adjacent fluidic structures and chambers) that the siphon exit functions as a capillary stop.

In another embodiment the valve is a microvalve which is able to be opened and resealed. For example a paraffin-based valve with an embedded micro-heater may be used.

In another embodiment, the side walls of the metering chamber border the expansion chamber.

In another embodiment, the side walls has a region closest to the rotational axis wherein the region borders to and opens into the expansion chamber.

In another embodiment, the central region of the metering chamber borders the expansion chamber.

In another embodiment, the central region has a zone closest to the rotational axis. wherein the region borders to and opens into the expansion chamber.

In another embodiment, the measuring chamber has a border between the metering chamber and the expansion chamber. The border is at least 5 time longer than the width of the valve.

In another example the microvalve may be a valve based on a ferrofluid such as is described in Park et al in the article “Multifunctional Microvalves Control by Optical Illumination on Nanoheaters and Its Application in Centrifugal Microfluidic Devices” in Lab Chip, 2007, 7, pages 557-564.

In another embodiment the fluidic structure is a microfluidic structure.

In another embodiment the step of increasing the rotational rate of the cartridge to transfer a first part of the fluid from the metering chamber through the valve comprises increasing the rotational rate of the cartridge to a first rotational rate to transfer the remaining part of the fluid back to the aliquoting chamber and increasing the rotational rate of the cartridge to a second rotational rate to transfer the first part of the fluid from the metering chamber through the valve. When the cartridge is rotated at a higher rate at the first rotational rate the centrifugal force becomes greater than any capillary force which is drawing fluid into the metering chamber. Fluid is then forced out of the metering chamber until the fluid level is equal with the lowest level of the duct exit. Increasing to the second rotational rate then forces the fluid through the valve. In some examples the valve is open. For example if a ferrofluid or a paraffin-based microvalve is used. This embodiment may have the benefit of increasing the accuracy of the fluid which is dispensed to the downstream fluidic element. As an alternative to this the cartridge is simply rotated at a rate which is fast enough to force the fluid through the valve. This may result in the amount of fluid being transferred to the downstream fluidic element if the first and second rotational rates are used. In another alternative if the valve is a controllably sealable or openable microvalve then the cartridge may be operated at a rotational rate to force the remaining part of the fluid back into the aliquoting chamber. After this is accomplished then the microvalve is opened and the rotation forces the fluid from the metering chamber into the downstream fluidic element. As an alternative it may be possible to replace the microvalve with a reusable siphon.

In some examples the fluid may be drawn into the metering chamber by capillary forces. The decrease in the rotational rate may cause the fluid to splash or move against the connecting duct and then the capillary forces may then fill the metering chamber. Increasing the rotational rate of the cartridge to transfer the first part of the fluid may have the effect of also cancelling any capillary forces which are drawing fluid into the metering chamber.

In another embodiment the step of increasing the rotational rate of the cartridge to transfer a first part of the fluid from the metering chamber through the valve comprises increasing the rotational rate of the cartridge to a first rotational rate to transfer the remaining part of the fluid back to the aliquoting chamber and increasing the rotational rate of the cartridge to a second rotational rate to transfer the first part of the fluid from the metering chamber through the valve. When the cartridge is rotated at a higher rate at the first rotational rate the centrifugal force becomes greater than any capillary force which is drawing fluid into the metering chamber. Fluid is then forced out of the metering chamber until the fluid level is equal with the lowest level of the duct exit. Increasing to the second rotational rate then forces the fluid through the valve. In some examples the valve is open.

In another embodiment, a ferrofluid or a paraffin-based microvalve is used. This embodiment may have the benefit of increasing the accuracy of the fluid which is dispensed to the downstream fluidic element. As an alternative to this the cartridge is simply rotated at a rate which is fast enough to force the fluid through the valve. This may result in the amount of fluid being transferred to the downstream fluidic element if the first and second rotational rates are used. In another alternative if the valve is a controllably sealable or openable microvalve then the cartridge may be operated at a rotational rate to force the remaining part of the fluid back into the aliquoting chamber. After this is accomplished then the microvalve is opened and the rotation forces the fluid from the metering chamber into the downstream fluidic element.

In another embodiment the step of increasing the rotational rate of the cartridge to transfer a second part of the fluid from the metering chamber through the valve comprises increasing the rotational rate of the cartridge to the first rotational rate to transfer the remaining part of the fluid back to the aliquoting chamber and increasing the rotational rate of the cartridge to the second rotational rate to transfer the second part of the fluid from the metering chamber through the valve.

In one example the aliquoting chamber has a depth of approximately 2.5 mm and a width of 4.0 mm. The height in the radial direction (towards the axis of rotation) may be 6 mm.

In one example the metering chamber may have depth of 0.8 mm and a width of 3.8 mm. The height without the expansion chamber may be approximately 7.0 mm.

In one example the second duct has a depth of 0.5 mm and a width of 1 mm. In other examples the depth of the second duct is between 0.1 mm and 1 mm. In other examples, the second duct has a width between 0.1 and 1.5 mm. The depth is in the direction of the axis of rotation and the width lies in the plane perpendicular to the axis of rotation.

In another aspect the invention, an embodiment provides for a cartridge for an automatic analyzer. The cartridge is operable for being spun around a rotational axis. The cartridge comprises a fluid chamber for receiving a fluid. The cartridge further comprises an aliquoting chamber. The cartridge further comprises a first duct connecting the fluid chamber and the aliquoting chamber. The cartridge further comprises a metering chamber operable for causing fluid to fill the metering chamber using capillary action.

The cartridge further comprises a second duct connecting the metering chamber with the aliquoting chamber. The second duct comprises a duct entrance in the aliquoting chamber. The second duct further comprises a duct exit in the metering chamber. The duct exit is closer to the rotational axis than the duct entrance. The second duct is operable for or designed such that it causes fluid to flow to the metering chamber using capillary action. The second duct may be made operable for causing fluid flow to the metering chamber by using a characteristic dimension which is small enough such that it results in capillary forces.

The cartridge further comprises a downstream fluidic element. The downstream fluidic element is connected to the metering chamber via a valve. The cartridge further comprises a fluidic structure for processing a biological sample into the processed biological sample. The fluidic structure comprises the downstream fluidic element. The downstream fluidic element is fluidically connected to the fluidic structure. The fluidic structure comprises a measurement structure for enabling measurement of the processed biological sample. The fluidic structure is configured for receiving the biological sample.

In another embodiment the aliquoting chamber has an upper portion and a lower portion. The upper portion is closer to the rotational axis than the lower portion. The metering chamber has an upper part. The metering chamber has a lower part. The upper part is closer to the rotational axis than the lower part. The duct exit is within the upper part of the metering chamber. The duct entrance is within the lower portion of the aliquoting chamber.

In another embodiment a cross-sectional view of the second duct and the aliquoting chamber is shaped similar to a watering can.

In another embodiment the metering chamber has a metering chamber surface. The metering chamber surface is at least partially rounded. In this embodiment the hard corners are avoided in the metering chamber to reduce the chances that a bubble forms or adheres within the metering chamber and to promote a complete filling of the metering chamber with fluid. It may be desirable to avoid bubbles in the metering chamber because bubbles change the volume of fluid that can be stored in the metering chamber. If bubbles form during the filling of the metering chamber this may result in an inconsistent amount of fluid being transferred to the downstream fluidic element.

In another embodiment the metering chamber has sidewalls and a central region. The sidewalls taper away from the central region. Having the sidewalls taper away from the central region may result in a larger capillary action near the sidewalls than in the central region area. This may cause the sidewalls to fill first with fluid and this may reduce the chances of bubbles forming in the metering chamber.

In other embodiments the metering chamber has sidewalls. A profile of the metering chamber tapers towards the sidewalls.

In another embodiment the capillary action next to the sidewalls of the metering chamber is greater than in the central region of the metering chamber. This may result in the sidewalls filling with fluid before the central region.

In another embodiment the sidewalls are operable for filling with fluid before the central region to prevent the formation and/or adherence of bubbles in the metering chamber.

In another embodiment the capillary action of the metering chamber is greater than the capillary action in the second duct. This may assist in filling the metering chamber with the fluid.

In another embodiment the cartridge further comprises an expansion chamber with a vent. The expansion chamber is fluidically connected to the metering chamber. The capillary action in the metering chamber is greater than the capillary action in the expansion chamber. The expansion chamber is nearer to the rotational axis than the metering chamber. The use of such an expansion chamber may allow air to uniformly exit the metering chamber. This may further reduce the chances of bubbles forming or adhering in the metering chamber.

In another embodiment the metering chamber has an upper edge or surface. The upper edge or surface is the boundary of the metering chamber that is closer to the rotational axis than the rest of the metering chamber. In this embodiment the whole upper section or boundary of the metering chamber may open into the expansion chamber. This may further reduce the chances of bubbles forming or adhering when filling the metering chamber.

In another embodiment the expansion chamber is closer to the rotational axis than the aliquoting chamber. This may be beneficial because it reduces the chances that the expansion chamber will fill with the fluid.

In another embodiment the cartridge further comprises a reservoir filled with the fluid. The reservoir is configured for being opened and for transferring the fluid to the fluid chamber. The cartridge may have for example a reservoir opening element that could be used for opening the reservoir. It may also be possible that an actuator could be used to actuate or activate the reservoir opening element. For instance an automatic analyzer may have a device which would cause the actuation of the reservoir or a mechanism attached to it in order to open the reservoir allowing the fluid contained in the reservoir to be entered into the fluid chamber.

The reservoir may for example be sealed with a removable or pierceable seal that could for example be a thin film or a foil. For example a small piece of metal foil or a thin film of plastic may be used as a pierceable seal. The fluid chamber or another component of the cartridge may have a piercing structure for opening the pierceable seal. The piercing structure may be any structure which is capable of piercing the particular pierceable seal and for instance could be a pin, a lance, or a sharp edge. In other examples the removable seal may be able to be peeled off to open the reservoir.

In another embodiment the fluid chamber or a fluid receiving structure connected to the fluid chamber is configured for receiving a dosing needle for dispensing the fluid to the fluid chamber. This for instance may be performed manually or an automatic analyzer may have a dosing needle which automatically dispenses fluid to the fluid chamber or the fluid receiving structure.

In another embodiment the fluid is any one of the following: a dispersion, a fluid comprising nanoparticles, a fluid comprising a blood grouping reagent, a fluid comprising an immune reagent, a fluid comprising an antibody, a fluid comprising an enzyme, a fluid comprising one or more substrates for an enzymatic reaction, a fluid comprising fluorescence emitting molecules, a fluid comprising molecules for measuring immunochemical reactions, a fluid comprising molecules for measuring reactions of nucleic acids, a fluid comprising a recombinant protein, a fluid comprising virus isolate, a fluid comprising a virus, a fluid comprising a biological reagent, a solvent, a diluent, a buffer, a fluid comprising a protein, a fluid comprising a salt, a detergent, a fluid comprising a fluid comprising a nucleic acid, a fluid comprising an acid, a fluid comprising a base, an aqueous solution, a non-aqueous solution, and combinations thereof.

In another embodiment the measurement structure comprises two or more electrodes and/or an optical measurement structure. The measurement system comprises a system for making an electrical measurement. The measurement system comprises a system for making optical measurements.

In some embodiments the optical measurement structure may be a transparent structure. The measurement system comprises an optical measurement system.

In some examples optically transparent may include the near infrared and near ultraviolet. In other examples optically transparent may exclude the near infrared or near ultraviolet.

Some examples may have both the measurement structure with the transparent structure and also the electrodes for more complicated tests. For example the measurement structure may be a structure for making electrochemiluminescence measurements where electrodes cause an optical excitation in a sample.

In other examples the measurement structure comprises two or more electrodes for making an electrical measurement or ECL measurement of the processed biological sample. For example, the measurement structures of Martinez-Duarte et. al. or Kim et. al. may be incorporated into a cartridge.

Examples may also only have electrode. For example, in an electrochemical detection structure, an electrode may be used to measure a current caused by the result of an enzymatic reaction.

In another embodiment the cartridge further comprises an excess fluid chamber connected to the aliquoting chamber via a fluidic connection. The fluidic connection comprises a fluidic connection entrance. The fluidic connection entrance is further away from the rotational axis than the duct exit. This may be beneficial because it means that the maximum level of the fluid in the aliquoting chamber is below the duct exit.

In another aspect the invention, an embodiment provides for an automatic analyzer configured for receiving a cartridge according to an embodiment. The automatic analyzer comprises a cartridge spinner, a measurement system, and a controller configured for controlling the automatic analyzer.

The controller is configured or programmed to control the cartridge spinner to control the rotational rate of the cartridge to process the biological sample into the processed biological sample using the fluidic structure. The controller is further configured or programmed to control the cartridge spinner to control the rotational rate of the cartridge to transport the fluid from the fluid chamber to the aliquoting chamber via the first duct.

The controller is further configured or programmed to control the cartridge spinner to force the fluid in the reservoir to flow into the second duct and to fill the metering chamber a first time. The controller is further configured or programmed to control the cartridge spinner to increase the rotational rate of the cartridge to transfer a first part of the fluid from the metering chamber through the valve and to transfer a first remaining part back into the aliquoting chamber. The controller is further configured or programmed to control the cartridge spinner to decrease the rotational rate of the cartridge to force the fluid in the reservoir to flow into the second duct and to fill the metering chamber a second time.

The controller is further configured or programmed to control the cartridge spinner to increase the rotational rate of the cartridge to transfer a second part of the fluid from the metering chamber through the valve and to transfer a second remaining part back into the aliquoting chamber. The controller is further configured or programmed to control the measurement system to perform the measurement using the measurement structure.

It is understood that one or more of the aforementioned embodiments of the invention may be combined as long as the combined embodiments are not mutually exclusive.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following embodiments of the invention are explained in greater detail, by way of example only, making reference to the drawings in which:

FIG. 1 illustrates fluidic elements for performing multiple aliquots of a fluid;

FIG. 2 illustrates a cross sectional view of a metering chamber;

FIG. 3 illustrates an example of a cartridge that incorporates the fluidic elements of FIG. 4 illustrates part of a method of performing a dispensing fluid using the fluidic elements of FIG. 1;

FIG. 5 further illustrates part of a method of performing a dispensing fluid using the fluidic elements of FIG. 1;

FIG. 6 further illustrates part of a method of performing a dispensing fluid using the fluidic elements of FIG. 1;

FIG. 7 further illustrates part of a method of performing a dispensing fluid using the fluidic elements of FIG. 1;

FIG. 8 further illustrates part of a method of performing a dispensing fluid using the fluidic elements of FIG. 1;

FIG. 9 further illustrates part of a method of performing a dispensing fluid using the fluidic elements of FIG. 1;

FIG. 10 further illustrates part of a method of performing a dispensing fluid using the fluidic elements of FIG. 1;

FIG. 11 illustrates an example of an automatic analyzer; and

FIG. 12 shows a flow chart which illustrates a method of operating the automatic analyzer of FIG. 11.

DETAILED DESCRIPTION

Like numbered elements in these figures are either equivalent elements or perform the same function. Elements which have been discussed previously will not necessarily be discussed in later figures if the function is equivalent.

For heterogeneous immunochemical assays a washing buffer is often required to perform separation or washing steps to increase test sensitivity and reproducibility. For clinical chemistry tests buffers are often required for sample dilution or biochemical reactions. According to Richtlinie der Bundesärztekammer (RiliBÄK) guidelines for Point of Care (POC) disposables all liquid reagents have to be pre-stored on the disposable. From such pre-storage containers, the released fluid volume is typically released at once. If the fluid volume has to be split into aliquots complicated space-consuming microfluidic structures are required. This space consumption often hinders the implementation of parallel microfluidic structure for panels into microfluidic disposables.

Further, valves typically used for disc format disposables like siphons, geometrical valves or hydrophobic valves can either be used one time only or special variants of siphons can be used several times but a fluid volume in the interconnected chamber is completely transferred through the valve without the possibility to split the volumes into aliquots. Therefore with state-of-the art valves it is not possible to release a fluid volume from a pre-storage containment into a microfluidic cavity featuring a siphon valve and split this volume into several aliquots.

A disadvantage with geometrical valves is that there is no control of fluids with decreased surface tension is possible. This is especially true for washing buffers.

A disadvantage with using hydrophobic valves is that there no control of fluids with decreased surface tension is possible. This is especially true for washing buffers. Hydrophobic valves also have the disadvantage that they can only be used once.

A disadvantage of state of the art siphons is that state of the art siphons can only be filled once. Air bubbles remaining in the siphon after this has been used inhibit a second filling of the siphon. Further the siphons will transfer the complete fluid volume located radially inwards of the siphon from an upstream chamber into a downstream fluidic element.

FIG. 1 shows a number of fluidic components 100. The fluidic components 100 are part of the fluidic components that make up a disc. There is a rotational axis labeled 102. Also shown in the Fig. is a portion of a fluid chamber 104. The fluid chamber either is designed for receiving fluid or for having a reservoir that provides fluid via a fluid chamber duct 106 that leads into the aliquoting chamber 108. In this example the aliquoting chamber 108 is well-shaped. There is a second duct 110 which connects the aliquoting chamber 108 with a metering chamber 112. The second duct 110 has a duct entrance 114 and a duct exit 116. The duct entrance 114 leads to the aliquoting chamber 108 and the duct exit 116 leads to the metering chamber 112. The duct entrance 114 is further from the rotational axis 102 than the duct exit 116 of the second duct.

The metering chamber 112 is connected via a tube 120 to a downstream fluidic element 122. In this example, there is a valve 121 between the tube 120 and the downstream fluidic element 122. The valve 121 in this example is a capillary valve. The valve 121 could be implemented in different ways. In some embodiments the tube 120 could functions as the capillary valve. In some embodiments a duct could be connected in the same location and a controllable microvalve could be used instead. The controllable microvalve could be placed between the metering chamber 112 and the tube 120 or between the tube 120 and the downstream fluidic element 122.

An expansion chamber 124 is shown as bordering on an upper edge 126 of the metering chamber 112. There is a vent 128 which vents the expansion chamber 124. The whole boundary between the metering chamber 112 and the expansion chamber 124 is open. This may help reduce the chances of bubbles forming in the metering chamber 112. In some examples the expansion chamber 124 may have a thickness which is greater than that of the metering chamber 112. Capillary forces may be used then to keep the fluid in the metering chamber 112. The dashed line labeled 130 and also A-A shows the location of a cross-sectional view of the metering chamber 112. This cross-sectional view is shown in FIG. 2. The aliquoting chamber 108 can be shown as also having a vent 128. The region around the duct entrance 114 is in this embodiment funnel-shaped. It may also be noted that the aliquoting chamber 108 is shown as not having sharp edges. The lack of sharp edges helps to facilitate the movement of fluid from the aliquoting chamber 108 to the duct entrance 114 when the disc is decelerated.

The aliquoting chamber 108 is also shown as having a connection to a fluidic connection 134 which leads to an excess fluid chamber 132. The fluidic connection 134 has a fluidic connection entrance 136. The fluidic connection entrance 136 defines the maximum fluid level in the aliquoting chamber 108. The maximum fluid level in the aliquoting chamber 108 is further from the rotational axis 102 than the duct exit 116. The fluidic connection 134 is connected to the excess fluid chamber 132 in this example. The use of a valve or a capillary valve is optional. The excess fluid chamber is shown as having a vent 128 and it is also connected to a failsafe chamber 140. When the fluid flows into the excess fluid chamber 132 the failsafe chamber 140 is filled. The failsafe chamber 140 may be used to indicate optically if fluid has entered the excess fluid chamber 132. For example, during use if the failsafe chamber 140 is not filled it may indicate that the aliquoting chamber 108 was not properly filled with fluid.

FIG. 2 shows a cross-sectional view 200 of the profile A-A which is labeled 130 in FIG. 1. In this Fig. the body of the cartridge 202 can be seen. There is an opening in the body 202 for the metering chamber 112. The body of the cartridge 202 in this example is fabricated by injection molding. The body of the cartridge is assembled from a lid 208 and a support structure 210.

At the far end of the metering chamber the entrance into the valve 121 can be seen. The metering chamber 112 can be seen as being divided into several different regions. On the edges there are two sidewalls regions 204. Between the two sidewalls regions or two side regions is a central region 206. The sidewall 204 regions become more narrow or taper away from the central region 206. This causes a narrowing in the dimensions of the metering chamber 112 in this region. The capillary action may therefore be higher in the sidewall regions 204 than in the central region 206. This may cause the metering chamber 112 to fill with fluid first in the sidewall region before the central region 206. This may have the benefit of using a number of bubbles which are formed or trapped in the metering chamber 112 when the metering chamber 112 is filled with fluid.

FIG. 3 shows the integration of the fluidic components 100 into a cartridge 300. The cartridge 300 is flat and disc-like and is shown as having a rotational axis 102. There is a fluid chamber 104 which is adapted or operable for receiving a fluid. The fluid reservoir 306 filled with a fluid 307 is sealed with a pierceable seal 308 in this example and there is a piercing element 310 on the wall of the fluid chamber 104. The fluid reservoir has a number of engaging surfaces or reservoir opening elements 312 which may be manipulated manually or by an apparatus such as an actuator which causes the pierceable seal 308 to contact the piercing element 310. This then causes the fluid chamber 104 to fill with the fluid 307. The fluid chamber 104 is shown as being connected to a first duct 106. The first duct 106 is connected to an aliquoting chamber 108. When the disc 300 is rotated about the rotational axis 102 centrifugal force forces fluid 307 through the duct 106. This then causes the aliquoting chamber 108 to fill with the fluid 307.

The aliquoting chamber 108 is shown as being connected to second duct 110 which leads to the metering chamber 112 as is shown in FIG. 1. In this example the aliquoting chamber 108 is laid out in a plane-like fashion aligned with the plane of the disc. The rotational axis is perpendicular to the plane. Attached to the aliquoting chamber 108 is an excess fluid container 132. This is an optional element.

The metering chamber 112 is shown as being connected to a downstream fluidic element 122 via a tube 120. There is however a valve 121 located between the metering chamber 112 and the tube 120. The downstream fluidic element 122 is part of a fluidic structure 336 for processing a biological sample into a processed biological sample.

The fluidic structure 336 comprises a number of fluidic elements 338 that are connected by various ducts and siphons 340. There are also a number of vents 342 within the fluidic structure 336. In this example there is an opening 346 which enables a biological sample to be placed into the fluidic structure 336. There is also a cover lid 348 which is used to close and seal the opening 346. The fluidic structure 336 also comprises a measurement structure 344 which allows a measurement to be made on the biological sample using a measurement system.

The measurement system may for instance be an optical, electrical, or a combination of the two systems for making the measurement on the processed biological sample.

The processing of the biological sample can be controlled by controlling the rotational rate about the rotational axis and duration. The siphons 340 are designed to be filled automatically using a capillary action. However, a sufficiently large rotational rate about the rotational axis 102 will produce a centrifugal force which will oppose the capillary action. Thus, by controlling the rotational rate and the duration of rotation at particular rates the processing of the biological sample can be controlled. In a typical usage the biological sample may be placed into the inlet 346 and the rotation rate of the system may be controlled. Then at some point an actuator or other mechanical means is used to manipulate the reservoir opening element and causes the piercing element 310 to pierce the pierceable seal 308. Rotation can then force fluid into the aliquoting chamber and a variety of rotational rates may be used to perform multiple aliquotations using the cartridge 300.

FIGS. 4-10 illustrate how the fluidic components 100 may be used to perform multiple aliquotations of fluid to the downstream fluidic element 122.

First, in FIG. 4, fluid has been added to the fluid chamber 104. The cartridge is then spun about the axis of rotation 102. This forces fluid 307 to travel through the first duct 106 into the aliquoting chamber 108. The fluid 307 then fills the aliquoting chamber 108 and the corresponding radially outwards portion of the second duct 110 with fluid.

FIG. 5 shows the cartridge spinning at the same rate and same direction 400 as was shown in FIG. 4. In FIG. 5, all the fluid has been drained out of the fluid chamber 104. The fluid 307 can be shown as filling the second duct 110 and the aliquoting chamber 108 to the maximum fluid level 500 which is set by the fluid connection entrance 136. Excess fluid 307 can be shown as being filled into the excess fluid chamber 132 and the failsafe chamber 140.

Next, in FIG. 6, the disc stops or slows its rate of rotation. Capillary action in the second duct 110 and the metering chamber 112 is shown as beginning to draw fluid into the metering chamber 112. The fluid 307 first fills the periphery or edge of the metering chamber 112. This helps preventing the formation or adhesion of bubbles within the metering chamber 112. When the cartridge is rapidly de-accelerated inertia of the fluid 307 may also help it to enter the metering chamber 112.

Next, in FIG. 7, the cartridge is shown as being still stationary or at a reduced rotation rate and the metering chamber 112 is completely filled with fluid 307. The cartridge or disc may still be considered to be at rest.

FIG. 8 shows the same view as is shown in FIG. 7 except a dashed line 800 has been drawn in the metering chamber 112. This line 800 in the metering chamber 112 divides the fluid in the metering chamber into several parts or portions. A part of the fluid volume or the whole fluid volume 804 radially inward (closer to axis of rotation 102) from the line 800 may flow back into the reservoir. The radially outward part (further from the axis of rotation 102) or part 802 may be transferred into the downstream fluidic element 122. The radially inward part 804 can be referred to as the remaining part of the fluid and the radially outward part 802 can be referred to as the part of the fluid 802 that is transferred into the downstream fluidic element 122. The volume of the fluid 802 is the aliquot.

Next, in FIG. 9, the disc begins to accelerate and spin around in the direction 400. The disc for instance may spin at the rate shown in FIGS. 1 and 2. The disc accelerates; this causes the capillary valve 121 to open. The remaining part of the fluid 804 was transferred back to the aliquoting chamber 108. The part of the fluid 802 is in the process of being transferred to the downstream fluidic element 122. A drop of the fluid can be seen dropping from the tube 120.

Next, in FIG. 10, it can be seen that the fluid volume 802 has been completely transferred to the downstream fluidic element 122 and is no longer visible in FIG. 10. The remaining part of the fluid 804 has been transferred into the aliquoting chamber 108 and is mixed with the fluid 307. The first aliquotation step is finished; the process may be repeated again from FIG. 6 and may be repeated until the fluid volume 307 in the aliquoting chamber 108 is smaller than the volume of the metering chamber 112.

FIG. 11 shows an example of an automatic analyzer. The automatic analyzer 1100 is adapted for receiving a cartridge 300. There is a cartridge spinner 1102 which is operable for rotating the cartridge 300 about the rotational axis 102. The cartridge spinner 1102 has a motor 1104 attached to a gripper 1106 which attaches to a portion of the cartridge 1108. The cartridge 300 is shown further as having a measurement or transparent structure 1110. The cartridge 300 can be rotated such that the measurement structure 1110 goes in front of a measurement system 1112 which can perform for example an optical measurement on the processed biological sample. The actuator 1104 as was shown previously is also shown in this figure. It can be used to open a fluid reservoir(s) in the cartridge 100. In some examples the actuator may be replaced with a dispenser with a dosing needle for filling the fluid chamber of the cartridge 300.

The actuator 1111, the cartridge spinner 1102, and the measurement system 1112 are shown as all being connected to a hardware interface 1116 of a controller 1114. The controller 1114 contains a processor 1118 in communication with the hardware interface 1116, electronic storage 1120, electronic memory 1122, and a network interface 1124. The electronic memory 1130 has a machine executable instructions which enables the processor 1118 to control the operation and function of the automatic analyzer 1100. The electronic storage 1120 is shown as containing a measurement 1132 that was acquired when instructions 1130 were executed by the processor 1118. The network interface 1124 enables the processor 1118 to send the measurement 1132 via network interface 1126 to a laboratory information system 1128.

FIG. 12 shows a flowchart which illustrates a method of operating the automatic analyzer 1100 of FIG. 11. First in step 1200 the commands 1130 cause the processor 1118 to control the cartridge spinner to control the rotation rate of the cartridge to process the biological sample into a processed biological sample using the fluidic structure. Next in step 1202 the commands 1130 cause the processor 1118 to control the cartridge spinner 1102 to control the rotation rate of the cartridge to transport the fluid from the fluid chamber to the aliquoting chamber via the first duct. Next in step 1204 the instructions 1130 cause the processor 1118 to control the cartridge spinner to force fluid in the reservoir to flow into the second duct and to fill the metering chamber a first time. Next in step 1106 execution of the instructions 1130 cause the processor 1118 to control the cartridge spinner 1102 to increase the rotational rate of the cartridge to transfer a first part of the fluid from the metering chamber through the valve and to transfer a first remaining part back into the aliquoting chamber. Next in step 1208 execution of the instructions 1130 cause the processor 1118 to control the cartridge spinner 1102 to decrease the rotational rate of the cartridge to force fluid in the reservoir to flow into the second duct and to fill the metering chamber a second time. Next in step 1210 execution of the instructions 1130 cause the processor to control the cartridge spinner to increase the rotational rate of the cartridge to transfer a second part of the fluid from the metering chamber through the valve and to transfer a second remaining part of the fluid back into the aliquoting chamber. Finally in step 1212 execution of the instructions 1130 cause the processor 1118 to control the measurement system 1112 to perform the measurement using the measurement structure.

LIST OF REFERENCE NUMERALS

-   -   100 fluidic components     -   102 rotational axis     -   104 fluid chamber     -   106 fluid chamber duct     -   108 aliquoting chamber     -   110 second duct     -   112 metering chamber     -   114 duct entrance     -   116 duct exit     -   120 tube     -   121 valve     -   122 downstream fluidic element     -   124 expansion chamber     -   126 upper edge     -   128 vent     -   130 profile A-A     -   132 excess fluid chamber     -   134 fluidic connection     -   136 fluidic connection entrance     -   140 fail safe chamber     -   200 cross sectional view A-A     -   202 body of cartridge     -   204 side walls     -   206 central region     -   208 lid     -   210 support structure     -   300 cartridge     -   306 fluid reservoir with fluid     -   307 fluid     -   308 pierceable seal     -   310 piercing element     -   312 engaging surface or reservoir opening element     -   336 fluidic structure     -   338 fluidic element     -   340 siphon     -   342 vent     -   344 measurement structure     -   346 opening     -   348 cover lid     -   400 arrow     -   500 maximum fluid level     -   800 dividing line     -   802 part of fluid     -   804 remaining part of fluid     -   1100 automatic analyzer     -   1102 cartridge spinner     -   1104 motor     -   1106 gripper     -   1108 portion of cartridge     -   1110 measurement structure     -   1111 actuator     -   1112 measurement system     -   1114 controller     -   1116 hardware interface     -   1118 processor     -   1120 electronic storage     -   1122 electronic memory     -   1124 network interface     -   1126 network connection     -   1128 laboratory information system     -   1130 executable instructions     -   1132 measurement     -   1200 control the rotational rate of the cartridge to process the         biological sample into the processed biological sample using the         fluidic structure;     -   1202 control the rotational rate of the cartridge to transport         the fluid from the fluid chamber to the aliquoting chamber via         the first duct;     -   1204 control the cartridge spinner to permit the fluid in the         aliquoting chamber to flow into the second duct and to fill the         metering chamber a first time;     -   1206 increase the rotational rate of the cartridge to transfer a         first part of the fluid from the metering chamber through the         valve and to transfer a first remaining part back into the         aliquoting chamber;     -   1208 decrease the rotational rate of the cartridge to permit the         fluid in the reservoir to flow into the second duct and to fill         the metering chamber a second time;     -   1210 increase the rotational rate of the cartridge to transfer a         second part of the fluid from the metering chamber through the         valve and to transfer a second remaining part back into the         aliquoting chamber; and     -   1212 perform the measurement using the measurement structure. 

What is claimed is:
 1. A method of repeatedly dispensing measured amounts of a fluid using a cartridge, wherein the cartridge is operable for being spun around a rotational axis, wherein the cartridge comprises: a metering chamber, wherein the metering chamber is operable for causing fluid to fill the metering chamber using capillary action, wherein the metering chamber has side wall regions and a central region, wherein the side wall regions are narrower than the central region in a cross sectional view of the metering chamber, wherein capillary action next to the side wall regions of the metering chamber is greater than in the central region of the metering chamber; a vent connected to the metering chamber, wherein the vent is nearer to the rotational axis than the metering chamber; and a duct connected to the metering chamber, wherein the duct comprises a duct entrance and a duct exit in the metering chamber, the duct exit being closer to the rotational axis than the duct entrance, wherein the duct is operable for causing fluid to flow to the metering chamber using capillary action, wherein the method comprises: decreasing a rotational rate of the cartridge to permit a fluid in the cartridge to flow through the duct and fill the metering chamber a first time; increasing the rotational rate of the cartridge to transfer both a first part of the fluid from the metering chamber and a first remaining part back through the duct exit; decreasing the rotational rate of the cartridge to permit the fluid to flow from the duct exit and fill the metering chamber a second time; and increasing the rotational rate of the cartridge to transfer both a second part of the fluid from the metering chamber and a second remaining part back through the duct exit.
 2. The method of claim 1, wherein increasing the rotational rate of the cartridge to transfer both the first part of the fluid from the metering chamber and the first remaining part back through the duct exit comprises increasing the rotational rate to a first rotational rate which transfers the first remaining part of the fluid back through the duct exit and increasing the rotational rate of the cartridge to a second rotational rate to transfer the first part of the fluid from the metering chamber.
 3. The method of claim 1, wherein increasing the rotational rate of the cartridge to transfer both the second part of the fluid from the metering chamber and the second remaining part back through the duct exit comprises increasing the rotational rate to a first rotational rate to transfer the second remaining part of the fluid back through the duct exit and increasing the rotational rate of the cartridge to a second rotational rate to transfer the second part of the fluid from the metering chamber.
 4. The method of claim 2, wherein increasing the rotational rate of the cartridge to transfer both the second part of the fluid from the metering chamber and the second remaining part back through the duct exit comprises increasing the rotational rate to a first rotational rate to transfer the second remaining part of the fluid back through the duct exit and increasing the rotational rate of the cartridge to a second rotational rate to transfer the second part of the fluid from the metering chamber.
 5. A cartridge operable for being spun around a rotational axis, wherein the cartridge comprises: a metering chamber, wherein the metering chamber is operable for causing fluid to fill the metering chamber using capillary action, wherein the metering chamber has side wall regions and a central region, wherein the side wall regions are narrower than the central region in a cross sectional view of the metering chamber, wherein capillary action next to the side wall regions of the metering chamber is greater than in the central region of the metering chamber; a vent connected to the metering chamber, wherein the vent is nearer to the rotational axis than the metering chamber; and a duct connected to the metering chamber, wherein the duct comprises a duct entrance and a duct exit in the metering chamber, the duct exit being closer to the rotational axis than the duct entrance, wherein the duct is operable for causing fluid to flow to the metering chamber using capillary action.
 6. The cartridge of claim 5, wherein the cartridge further comprises a fluid chamber for receiving the fluid into the cartridge, the metering chamber being in fluid communications with the fluid chamber.
 7. The cartridge of claim 5, wherein the cartridge further comprises a vent connected to the metering chamber, wherein the vent is nearer to the rotational axis than the metering chamber.
 8. The cartridge of claim 5, wherein the metering chamber has a metering chamber surface, wherein the metering chamber surface is rounded.
 9. The cartridge of claim 5, wherein the capillary action in the metering chamber is greater than the capillary action in the duct.
 10. The cartridge of claim 5, wherein the cartridge further comprises a measurement structure with two or more electrodes and/or an optical measurement structure, the measurement structure being connected downstream from the metering chamber.
 11. The cartridge of claim 5, wherein the side wall regions are operable to be filled with the fluid before the central region in order to prevent formation and/or adherence of bubbles in the metering chamber.
 12. The cartridge of claim 5, wherein the metering chamber has an upper part and a lower part, the upper part being closer to the rotational axis than the lower part.
 13. The cartridge of claim 12, wherein the duct exit is within the upper part of the metering chamber.
 14. The cartridge of claim 5, wherein the cartridge further comprises an aliquoting chamber, wherein the duct connects the metering chamber with the aliquoting chamber.
 15. The cartridge of claim 14, wherein the duct entrance is in the aliquoting chamber.
 16. The cartridge of claim 14, wherein the cartridge further comprises an excess fluid chamber connected to the aliquoting chamber via a fluidic connection, wherein the fluidic connection comprises a fluidic connection entrance, and wherein fluidic connection entrance is further away from the rotational axis than the duct exit.
 17. The cartridge of claim 14, wherein the aliquoting chamber has an upper portion and a lower portion, wherein the upper portion is closer to the rotational axis than the lower portion.
 18. The cartridge of claim 17, wherein the duct entrance is within the lower portion of the aliquoting chamber.
 19. The cartridge of claim 5, wherein the cartridge further comprises an expansion chamber, the expansion chamber being connected to the metering chamber.
 20. The cartridge of claim 19, wherein capillary action in the metering chamber is greater than capillary action in the expansion chamber.
 21. The cartridge of claim 19, wherein the cartridge further comprises an aliquoting chamber, wherein the duct connects the metering chamber with the aliquoting chamber, and the expansion chamber is nearer to the rotational axis than the metering chamber.
 22. The cartridge of claim 21, wherein the expansion chamber is closer to the rotational axis than the aliquoting chamber.
 23. The cartridge of claim 5, wherein the cartridge further comprises a reservoir filled with the fluid, and wherein the reservoir is configured to be opened to transfer the fluid to the metering chamber.
 24. The cartridge of claim 23, wherein the fluid is any one of the following: a dispersion, a fluid comprising nanoparticles, a fluid comprising a blood grouping reagent, a fluid comprising an immune reagent, a fluid comprising an antibody, a fluid comprising an enzyme, a fluid comprising one or more substrates for an enzymatic reaction, a fluid comprising fluorescence emitting molecules, a fluid comprising molecules for measuring immunochemical reactions, a fluid comprising molecules for measuring reactions of nucleic acids, a fluid comprising a recombinant protein, a fluid comprising virus isolate, a fluid comprising a virus, a fluid comprising a biological reagent, a solvent, a diluent, a buffer, a fluid comprising a protein, a fluid comprising a salt, a detergent, a fluid comprising a fluid comprising a nucleic acid, a fluid comprising an acid, a fluid comprising a base, an aqueous solution, a non-aqueous solution, and combinations thereof.
 25. A system comprising: a cartridge spinner configured to receive and rotate a cartridge according to claim 5; and a controller electrically connected to the cartridge spinner and configured to: control the cartridge spinner to permit a fluid in the cartridge to flow through the duct to fill the metering chamber a first time; control the cartridge spinner to increasing the rotational rate of the cartridge to transfer a first part of the fluid from the metering chamber and to transfer a first remaining part back through the duct; control the cartridge spinner to decrease the rotational rate of the cartridge to permit the fluid to flow through the duct to fill the metering chamber a second time; and control the cartridge spinner to increasing the rotational rate of the cartridge to transfer a second part of the fluid from the metering chamber and to transfer a second remaining part back through the duct. 